The correct answer is: C. the income of the consumer does not change.
The ceteris paribus clause in the law of demand states that all other factors that might affect demand remain constant while the price of the good changes. This means that the income of the consumer is not included in the ceteris paribus clause.
If the income of the consumer changes, it will affect the demand for the good. For example, if the income of the consumer increases, they will be able to afford to buy more goods, including the good in question. This will increase the demand for the good. Conversely, if the income of the consumer decreases, they will be able to afford to buy fewer goods, including the good in question. This will decrease the demand for the good.
Therefore, the ceteris paribus clause in the law of demand does not mean that the income of the consumer does not change.